The oligosaccharide moiety of two glycopeptides obtained by pronase digestion of rabbit pulmonary angiotensin-converting enzyme will be structurally characterized using periodate oxidation and cleavage by specific exoglycosidases. Peptide fragments of the enzyme prepared by treatment with cyanogen bromide will be purified, structurally characterized, and used as immunoadsorbents to fractionate antiholoenzyme antibody into populations directed against different segments of the enzyme.